JVC KS-FX725R User manual

SERVICE MANUAL
CASSETTE RECEIVER
No.49721
Mar. 2002
COPYRIGHT 2002 VICTOR COMPANY OF JAPAN, LTD.
KS-FX725R
KS-FX725R
Area Suffix
EE ---- Russian Federation
Contents
Safety precaution
Disassembly method
Adjustment method
Description of major ICs
1-2
1-3
1-18
1-22
MO
TP
TP
RDS
RDS
PTY
PTY
DISP
DISP
8 9 10 11 127
DAB

1-2
KS-FX725R
!Burrs formed during molding may be left over on some parts of the chassis. Therefore,
pay attention to such burrs in the case of preforming repair of this system.
Safety precaution

1-3
KS-FX725R
Press the eject button in the lower right part of the
front panel. Remove the front panel assembly from
the body.
1.
Removing the front panel assembly
(See Fig.1)
Prior to performing the following procedure, remove
the front panel assembly.
Release the four joints aon both sides of the front
chassis assembly and remove the front chassis
assembly toward the front.
1.
Removing the front chassis assembly
(See Fig.2 , 3)
Disassembly method
<Main body>
Fig.1
Fig.2
Fig.3
Front panel assembly
Eject button
Joint a
Joint a
Front chassis assembly
Front chassis
assembly
Heat sink
Joint a
Joint a

1-4
KS-FX725R
Remove the three screws Aon the left side of the
body.
1.
Removing the heat sink (See Fig.4)
Prior to performing the following procedure, remove
the front panel assembly, the front chassis assembly
and the heat sink.
Turn over the body and unjoint the five joints bwith
the bottom cover and the body using a screwdriver.
1.
Removing the bottom cover
(See Fig.5 , 6)
When disengaging the joint cusing a
screwdriver, do not damage or break the
board.
CAUTION:
Fig.4
Fig.5
Fig.6
Heat sink
AA
Joint b
Joint b
Joint c
Joint b
Joint b
Joint c
Bottom cover
Bottom cover
Rear panel
Rear panel

1-5
KS-FX725R
Prior to performing the following procedure, remove
the front panel assembly, the front chassis assembly,
the heat sink and the bottom cover.
Remove the screw B, the three screws C and the
two screws Dattaching the rear bracket on the back
of the body. Remove the rear panel.
Remove the two screws Eattaching the main board
on the bottom of the body. Disconnect connector
CP401 on the main board in the direction of the
arrow.
1.
2.
Removing the main board (See Fig.7 , 8)
Prior to performing the following procedure, remove
the front panel assembly, the front chassis assembly,
the heat sink, the bottom cover and the main board.
Remove the four screws Fattaching the cassette
mechanism section on the back of the top chassis.
1.
Removing the cassette mechanism section
(See Fig.9)
Fig.7
Fig.8
Fig.9
Rear panel
B
D
D
C
C
Main board
E
E
CP401
Cassette mechanism section
FF
FF
Top chassis

1-6
KS-FX725R
Prior to performing the following procedure, remove
the front panel assembly.
Remove the four screws Gattaching the rear cover
on the back of the front panel assembly.
Unjoint the ten joints dwith the front panel and the
rear cover.
Remove the control switch board on the back of the
front panel.
1.
2.
3.
Removing the control switch board
(See Fig.10 ~ 12)
Fig.10
Fig.11
Fig.12
G G
GG
Rear cover
Joint d
Joint d Joint d
Joint d
Front panel
Rear cover
Front panel
Control switch board

1-7
KS-FX725R
Remove the screw Aattaching the reinforce bracket
on the bottom of the body.
To release joint a, turn and detach the reinforce
bracket from the side bracket assembly as shown in
Fig.2
1.
2.
Removing the reinforce bracket
(See Fig.1 and 2)
Turn the mode gear to set to RVS play or
subsequent mode.
Remove the cassette guide from the main chassis
while releasing each two joint tabs bin the direction
of the arrow.
1.
2.
Removing the cassette guide (See Fig.3)
Remove the screw Bon the upper side. Unsolder
the wires on the under side of the head board, if
necessary.
1.
Removing the head board (See Fig.4)
Prior to performing the following
procedures, turn the mode gear on the
bottom of the body until the respective part
comes to the EJECT position (Refer to
Fig.1).
REFERENCE:
When reassembling, twist the wires by
turning the head board twice remarked c
and pass through the notch das shown
in Fig.4.
REFERENCE:
Head board
Fig.1
Fig.2
Fig.4Fig.3
Mode gear
Reinforce bracket
Reinforce bracket
Joint a
Cassette guide
Tab b
Tab b
B
Head board
notch d
c
Soldering
A

1-8
KS-FX725R
Check the mode is set to EJECT. Push down the
front part of the cassette holder and move in the
direction of the arrow to release the joint f.
Move the rear part of the cassette hanger assembly
in the direction of the arrow to release it from the two
joint bosses g.
Release the holder stabilizer spring from the hooks h
and i, then pull out from the cassette hanger
assembly.
Bring up the rear side of the cassette hanger
assembly to release the joint jand k.
Pull out the cassette catch from the cassette hanger
assembly.
1.
2.
3.
4.
5.
Removing the cassette hanger assembly /
cassette holder (See Fig.6 to 9)
Remove the E-washer attaching the load arm.
Move the load arm in the direction of the arrow and
release the joint eon the cassette catch.
1.
2.
Removing the load arm (See Fig.5)
Fig.5
Fig.6
Fig.7
Fig.9
Fig.8
Load arm
E-washer
Joint e
Cassette holder assembly
Cassette holder assembly
Side bracket
Joints f
Cassette holder assembly
Cassette hanger assembly
Cassette hanger assembly
Cassette hanger
assembly
Boss g
Boss g
Cassette hanger assembly
Cassette stabilizer spring
Hook i
Hook k
Hook h
Hook j
Cassette holder
assembly Cassette catch

1-9
KS-FX725R
Remove the screw Cattaching the side bracket
assembly.
Detach the front side of the side bracket assembly
upward and pull out forward to release the joint land
min the rear.
1.
2.
Removing the side bracket assembly
(See Fig.10 to 12)
When reassembling, make sure that the
boss nof the main chassis is set in the
notch of the load rack under the side
bracket assembly. Do not reattach the
load rack on the boss n.
CAUTION:
After reattaching the side bracket
assembly, confirm operation.
CAUTION:
Fig.11
Fig.12
Fig.10
C
Side bracket assembly
Side bracket assembly
Joint l
Joint m
Side bracket assembly
Boss n
Load rack
Boss n
Load rack
Joint l
Joint m

1-10
KS-FX725R
Remove the polywasher and pull out the pinch arm
(F) assembly.
Remove the compulsion spring.
1.
2.
Removing the pinch arm (F) assembly
(See Fig.13 and 14)
Remove the polywasher and pull out the pinch arm
(R) assembly.
1.
Removing the pinch arm (R) assembly
(See Fig.13 and 15)
Move the slide chassis assembly in the direction of
the arrow to release the two joints oand remove
from the main chassis.
Remove the rack link.
1.
2.
Removing the slide chassis assembly
(See Fig.16 and 17)
When reassembling, first reattach the rack
link, and next fit the boss pand hook qof
the slide chassis assembly to the hole of the
main chassis, and engage the two joints o.
CAUTION:
It is not necessary to remove the head
and the tape guide.
REFERENCE:
Fig.13
Fig.17
Fig.14
Fig.15
Fig.16
Polywasher
Polywasher Pinch arm
(F) assembly
Pinch arm
(R) assembly
Polywasher
Pinch arm (F) assembly
Compulsion spring
Pinch arm
(R) assembly Polywasher
Slide chassis assembly
Joint o
Joint o
Boss p
Hook q
Rack link
Head
Tape guide

1-11
KS-FX725R
Remove the band attaching the wire to the head.
Remove the two screws D, the head and the head
support spring.
Remove the pinch arm spring from the tape guide.
Remove the tape guide and the pinch spring arm.
1.
2.
3.
4.
Removing the head / tape guide
(See Fig.18 and 19)
Remove the belt at the bottom.
Remove the two polywashers on the upper side.
Pull out each flywheel assembly downward.
1.
2.
3.
Removing the flywheel assembly (F) & (R)
(See Fig.20 and 21)
When reattaching the pinch arm spring, set
both end of it to the pinch spring arm (
remarked r).
CAUTION:
When reattaching the head, set the wires
into the groove of the tape guide (Fig.18).
CAUTION:
It is not necessary to remove the slide
chassis assembly.
REFERENCE:
It is not necessary to remove the slide
chassis assembly.
REFERENCE:
Fig.19
Fig.21
Fig.18
Fig.20
D
Slide chassis assembly
Head Tape guide
D
Pinch arm spring
Head
Head support spring
Tape guide
Pinch spring arm
Slid chassis assembly
Flywheel assembly (F)
Flywheel assembly (R)
Belt Polywasher
Polywasher
Flywheel assembly (F)
Flywheel assembly (R)
r
r

1-12
KS-FX725R
Push and turn counterclockwise the spring holder (F)
to release the three joints son the bottom of the
flywheel.
The spring holder (F), the TU spring and the friction
gear play come off.
Remove the polywasher and felt.
1.
2.
3.
Disassembling the flywheel assembly (F)
(See Fig.22 and 23)
Push and turn clockwise the spring holder (R) to
release the three joints ton the bottom of the
flywheel.
The spring holder (R), the FF spring and the friction
gear FF come off.
Remove the polywasher and the felt.
1.
2.
3.
Disassembling the flywheel assembly (R)
(See Fig.22 and 24)
Remove the two screws Eattaching the reel board.
Move the reel board in the direction of the arrow to
release the joint u.
Unsolder the wires if necessary.
1.
2.
3.
Removing the reel board
(See Fig.25 and 26)
When reattaching, confirm operation of
the MODE switch and the ST-BY switch.
The mode position between EJECT and
ST-BY is optimum for reattaching.
Connect the card wire extending from
the reel board to the FFC pad before
reattaching the reel board.
CAUTION:
Fig.26
Fig.22
Fig.23 Fig.24
Fig.25
Flywheel assembly (F) Flywheel assembly (R)
Joints s
Joint s
Joints t
Joint t
Polywasher
Spring holder (F)
TU spring
Polywasher
Spring holder (R)
FF spring
Friction gear play
Friction gear FF
Flywheel assembly (F) Flywheel assembly (R)
FFC pad
FFC pad
Joint u
Reel board
E
E
CT-1 switch
ST-BY switch
Soldering
MODE switch
Felt Felt

1-13
KS-FX725R
Move the gear base arm in the direction of the arrow.
Insert a slotted screwdriver to the gear base spring
under the gear base arm, and release the gear base
arm upward from the boss on the gear base
assembly.
Remove the gear base arm from the main chassis
while releasing the two joints v.
Move the gear base link assemby in the direction of
the arrow to release the two joints w.
1.
2.
3.
4.
Removing the gear base arm / gear base
link assembly (See Fig.27 to 29)
Push each joint hook xof the FFC pad and remove
toward the bottom.
1.
Removing the FFC pad
(See Fig.27 and 29)
When reattaching the gear base arm,
make sure that the boss on the gear
base assembly is inside the gear base
spring.
REFERENCE:
Fig.27
Fig.28
Fig.29
FFC pad
Gear base link assembly Gear base arm
Gear base
link assembly
Gear base arm
FFC pad
Joint w
Joint w
Joints v
Hook x
Hook x
Gear base arm
Screwdriver
Gear base spring

1-14
KS-FX725R
Remove the polywasher on the bottom and pull out
the mode gear.
1.
Removing the mode gear
(See Fig.30 and 33)
Move the mode rack assembly in the direction of the
arrow to release the two joints k’ and the joint l’.
1.
Removing the mode rack assembly
(See Fig.31 and 32)
Remove the polywasher attaching the direction link.
Bring up the direction link to release the three joints
a’, b’ and c’ at a time.
Move the direction plate in the direction of the arrow
to release the two joints d’.
1.
2.
3.
Removing the direction link / direction
plate (See Fig.31 to 33)
When reattaching, set the two k’ on the
bottom of the mode rack assembly into the
slots of the main chassis and move in the
direction of the arrow (See Fig.32).
REFERENCE:
Pull out the mode switch actuator at the bottom.
1.
Removing the mode switch actuator
(See Fig.30, 31 and 33)
When reattaching the mode switch
actuator to the main chassis, make sure to
set on the shaft and insert yinto the slot z.
REFERENCE:
When reattaching the direction plate,
engage the two joints d’ and move in the
direction of the arrow (See Fig.32).
REFERENCE:
When reattaching the direction link,
move the direction plate in the direction
of the arrow and engage the three joint
a’, b’ and c’ at a time (See Fig.33).
REFERENCE:
Fig.30
Fig.32
Fig.33
Fig.31
Polywasher
Mode switch actuator Mode gear
Direction plate Direction link
Mode rack assembly
Slot z
Direction plate
Joints d'
Joint c'
Direction link Polywasher
Joint b' Joint a'
Direction plate Mode rack assembly
Joint l'
Joint k'
Joint k'
Polywasher
Mode gear
Mode switch actuator
Direction link
Joints d'
Direction plate
Mode rack assembly
y

1-15
KS-FX725R
Push in the pin e’of the gear base assembly on the
upper side of the body and move the reflector gear
toward the bottom, then pull out.
Remove the polywasher on the bottom and pull out
the take up gear.
Move the gear base assembly in the direction of the
arrow to release it from the two slots f’of the main
chassis.
1.
2.
3.
Removing the gear base assembly / take
up gear / reflector gear (See Fig.34 to 36)
Draw out the reel driver from the shaft on the main
chassis and remove the reel driver spring and the
reel spindle respectively.
1.
Removing the reel driver / reel spindle
(See Fig.36)
The reel driver is damaged when
removed. Please replace with a new
one.
CAUTION:
The parts are damaged when removed.
Please replace with new ones.
REFERENCE:
Fig.34
Fig.35
Fig.36
Gear base assembly
Pin e'
Slot f'
Slot f'
Polywasher
Reflector gear
Take up gear
Reel driver spring
Reel driver spring
Reel driver
Reel driver
Reel spindle
Reel spindle
Gear base assembly
Slots f’
Main chassis
Reflector gear Polywasher
Take up gear

1-16
KS-FX725R
Remove the eject cam plate spring.
Push the joint g‘through the slot to remove the load
rack downward.
Move the eject cam limiter in the direction of the
arrow to release it from the boss h’of the side
bracket assembly and from the two joints i’.
Move the eject cam plate in the direction of the arrow
to release the joint j’.
1.
2.
3.
4.
Removing the side bracket assembly
(See Fig.37 to 41)
When reassembling, confirm operation of
each part before reattaching the eject cam
plate spring.
CAUTION:
Fig.37
Fig.39
Fig.41
Fig.38
Fig.40
Joint g'
Load rack
Eject cam plate spring
Eject cam limiter
Side bracket assembly
Boss h'
Joint i'
Load rack
Joint g'
Joint i'
Boss h'Eject cam limiter
Side bracket assembly
Joint i' Joint i'
Eject cam plate
Side bracket assembly
Boss h'
Joint j'
Eject cam plate
Side bracket assembly
Eject cam plate
Joint j'

1-17
KS-FX725R
Remove the belt at the bottom.
Remove the polywasher and pull out the mode gear.
Pull out the reduction gear (B).
Remove the polywasher and pull out the reduction
gear (A).
Remove the two screws Fattaching the main motor
assembly.
Remove the two screws Gattaching the sub motor
assembly.
Unsolder the wires on the reel board if necessary.
1.
2.
3.
4.
5.
6.
7.
Removing the main motor assembly /
sub motor assembly (See Fig.42 to 44)
When reassembling, adjust the length of the
wires extending from the sub motor
asswmbly by attaching them to the side of
the sub motor assembly with the wires
extending from the main motor assembly
using a spacer.
CAUTION:
Fig.42
Fig.43
Fig.44
Belt
Polywasher
Polywasher
Polywasher
Mode gear
Reduction
gear (A)
Main motor
assembly
F
Sub motor
assembly
G
Reduction gear (B)
Reduction gear (B)
Reduction gear (A)
GF
Main motor assembly
Sub motor assembly
Spacer
Spacer
Sub motor assembly
Main motor assembly

1-18
KS-FX725R
Adjustment method
Test instruments reqired for adjustment
1. Digital osclloscope(100MHz)
2. Frequency Counter meter
3. Electric voltmeter
4. Wow & flutter meter
5.Testtapes
VT724.......................
...................
for DOLBY level measurement
VT739............For playback frequency measurement
VT712....For wow flutter & tape speed measurement
VT703..................... For head azimuth measurement
6.Torquegauge ....................Cassette type for CTG-N
(mechanism adjustment)
Measuring conditions(Amplifier section)
Power supply voltage.............. DC14.4V (11V to 16V allowance)
Line-OutLevel/Impedance.......2.0V/20k load(250 nWb/m)...........
Standard volume position
Balance and Bass,Trable volume, Fader
:Center(Indication"0")
Loudness,Dolby NR,Sound,Cruise:Off
Volume position is about 2V at speaker output with
following conditions.Playback the test tape VT721.
FM1/FM2: 87.5MHz to 108.0MHz
FM3 : 65MHz to 74 MHz
AM : (MW)522kHz to1620kHz
(LW) 144kHz to 279kHz
MC-109C for TAPA CURL confirmation
(without Padd type)

1-19
KS-FX725R
Head section view
Cassette mechanism
(Surface)
Arrangement of adjusting & test points
Motor assembly
Tape speed adjust
Playback head
Azimuth screw B
(Reverse)
Azimuth screw B
(Reverse) Azimuth screw A (Forward)
Azimuth screw A
(Forward)
Playback Head

1-20
KS-FX725R
C401
C402
C403 C404
C405 C406
C407
C408
C409
C410
C411
C412
C413 C414 C416
C417
C418
C419
C421
C422
C423
C424
C425
CJ401
B405
B403
D401 D402
IC402
Q401
Q402
Q403
R401
R402
R403
R404 R405
R406
R407
R408
R410
R411
R412
R413
R414
R415
R416
R417
R418
R420
B413
R422
R423
R424
R425
R426
VR401
VR402
IC401
CJ403
B412
B407
B401
B408
B410
B406
B409 B404
C415
B402
B411
2
1
2
1
11
21
31
1
FSMW1093A
1
1
T11
VR401:Rch
(Dolby NR Frequency response adj)
Arrangment of adjusting
Head amplifier board section (Reverse side)
Information for using a car audio service jig
1. We're advancing efforts to make our extension cords common for all car audio products.
Please use this type of extension cord as follows.
2. As a U-shape type top cover is employed, this type of extension cord is needed to check operation of the
mechanism assembly after disassembly.
3. Extension cord : EXTKSRT002-18P ( 18 pin extension cord ) For connection between mechanism assembly
and main board assembly.
Check for mechanism driving section such as motor ,etc..
Disassembly method
1. Remove the bottom cover.
2. Remove the front panel assembly.
3. Remove the top cover .
4. Install the front panel.
5. Confirm that current is being carried by connecting
an extension cord jig.
Note
Available to connect to the CP701 connector when in-
stalling the front panel.
Cassette mechanism
Front panel assembly
EXTKSRT002-18P
Extension cord
Main board
VR402:Rch
(Dolby NR leveladj)
EXTKSRT002-18P
to Main board
to Cassette mechanism